How does insert update work?
Introduction to the MySQL INSERT ON DUPLICATE KEY UPDATE statement
- If the new row is inserted, the number of affected rows is 1.
- If the existing row is updated, the number of affected rows is 2.
- If the existing row is updated using its current values, the number of affected rows is 0.
How do you know if the record exists before INSERT to avoid duplicates?
6 Answers
- You can check for the record’s existence first and skip the INSERT if it is found, or.
- You can set the UNIQUE INDEX to “ignore” duplicates in which case you don’t need to check first as the operation will silently fail, with just a warning that the duplicate was not inserted.
What is the affected-row value in on duplicate key update?
With ON DUPLICATE KEY UPDATE, the affected-rows value per row is 1 if the row is inserted as a new row, 2 if an existing row is updated, and 0 if an existing row is set to its current values.
When to use auto increment on duplicate key update?
ON DUPLICATE KEY UPDATE inserts or updates a row, the LAST_INSERT_ID() function returns the AUTO_INCREMENT value. The ON DUPLICATE KEY UPDATE clause can contain multiple column assignments, separated by commas.
How to on duplicate key update in MySQL?
If you specify an ON DUPLICATE KEY UPDATE clause and a row to be inserted would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row occurs. For example, if column a is declared as UNIQUE and contains the value 1, the following two statements have similar effect: Press CTRL+C to copy.
How to set duplicate value in phpMyAdmin?
In phpmyadmin go to the structure. Down in inexes click on go. index name set the same name like column for UNIQUE value. In this table chose column for UNIQUE value. The value that will not be repeated is set in the db in the indexes. Behind the sentence: ON DUPLICATE KEY UPDATE, here you set values that can be adjusted.